Method and apparatus for detecting worn universal joint components

ABSTRACT

A method and apparatus for detecting the operating condition of a universal joint in a driveline assembly utilizes a pressure relief valve that is supported by a universal joint cross member. The cross member includes a central body portion with a plurality of radially extending trunnions. A first driveline component supports a first yoke member and a second driveline component supports a second yoke member. Each yoke member cooperates with two opposing trunnions to interconnect the first and second driveline components. An internal lubrication channel is formed within the cross member and is in fluid communication with each trunnion. Seal assemblies are installed within cups mounted to each trunnion member to seal the lubricating fluid within the cross member. The universal joint is operating properly when lubricating fluid that is injected through an external lubrication fitting during service operations, exits via the pressure relief valve. The universal joint is not operating properly when the lubricating fluid exits via at least one of the seal assemblies instead of through the pressure relief valve.

BACKGROUND OF THE INVENTION

This invention generally relates to a method and apparatus for servicinga universal joint assembly installed in a vehicle driveline to detectworn components.

Vehicle drivelines include at least one driveshaft that is used totransmit power from a vehicle engine and transmission to a single driveaxle or tandem drive axle. Typically, heavy-duty vehicles, such as largetrucks, include more than one driveshaft due to the long wheelbaseand/or use of a tandem drive axle. At each end of a driveshaft,universal joints (U-joints) are used to connect the driveshaft to thenext driveline component. For example, U-joints can be used to connectone driveshaft to another driveshaft or can be used to connect adriveshaft to a drive axle component.

U-joints allow two driveline components to be positioned at differentangles relative to each other to accommodate relative movement andangular misalignment. Further, as the drive axles cooperate with avehicle suspension to dampen shocks from rough road conditions, theU-joints provide flexibility to allow the adjoining driveline componentsto move relative to one another.

Typically, U-joints include two yokes that each have two bore locationsat diametrically opposed positions. The yokes are each mounted to twotrunnions on a center cross member. The combination allows the two yokesto move angularly relative to each other with respect to the center ofthe cross member.

In order for the U-joint to operate properly overlong periods of time,it is important to have good lubrication. The center cross membertypically includes an external grease fitting that is in fluidcommunication with each of the trunnion members via internal greasegrooves or channels. Bearing packs are mounted on each of the trunnionsand receive lubrication through the grease grooves. The bearing packsinclude a seal assembly that seals the grease within the center crossmember.

It is often difficult to detect when U-joint components have wornsufficiently, such that repair or replacement operations are required.Currently, to detect worn seals, the U-joint must be completelydisassembled and inspected. This process is time consuming and laborintensive, which results in increased service costs and vehicledowntime, both of which are undesirable.

Thus, it would be valuable to have a simple and efficient inspectionprocedure to detect worn U-joint components without having todisassemble the U-joint. The method and apparatus to detect worncomponents should be easily incorporated into existing U-joints withoutsignificant increases in cost.

SUMMARY OF THE INVENTION

A serviceable, permanently lubed, universal joint assembly utilizes afluid pressure member to detect the operating condition of a universaljoint assembly during a service operation. The universal joint assemblyincludes a cross member having a plurality of trunnions that cooperatewith yoke members supported by adjacent driveline components. Eachtrunnion supports a seal and bearing assembly which are mounted within acap installed over a distal end portion of the trunnion.

The operating condition of the internal components, such as bearings andseals, can be easily detected without having to disassemble theuniversal joint assembly. A lubricating fluid is injected into the crossmember via an external lubrication fitting. A properly operatinguniversal joint assembly is detected when lubricating fluid exits thefluid pressure member, and an improperly operating universal jointassembly is detected when the lubricating fluid exits at least one ofthe seal assemblies instead of the fluid pressure member.

In the preferred embodiment, the cross member includes a central bodyportion with a first pair of trunnions coupled to a first yoke memberand a second pair of trunnions coupled to a second yoke member. Thecross member includes an internal lubrication channel that is in fluidcommunication with each of the trunnions. An external lubricationfitting is supported by the cross member and is in fluid communicationwith the internal lubrication channel. The fluid pressure member issupported by the cross member and also is in fluid communication withthe internal lubrication channel. An internal fluid pressure isgenerated within the cross member in response to a lubricating fluidbeing injected into the internal lubrication channel via the externallubrication fitting. A first operating condition is indicated when theinternal fluid pressure is below a predetermined pressure value and asecond operating condition, different than the first operatingcondition, is indicated when the internal fluid pressure exceeds thepredetermined pressure value.

As discussed above, each of the trunnions includes a seal assembly thatseals the lubricating fluid within the internal lubrication channel.Each seal assembly has a predetermined initial sealing force that isgreater than the predetermined pressure value. The first operatingcondition is defined as the improperly operating universal joint andoccurs when at least one of the seal assemblies has an operating sealingforce that is less than the predetermined initial sealing force and lessthan the predetermined pressure value, such that the lubricating fluidexits the cross member through the defective seal assembly instead ofthrough the fluid pressure member. The second operating condition isdefined as the properly operating universal joint and occurs when theinternal fluid pressure achieves the predetermined pressure value, whichactivates the fluid pressure member and allows lubricating fluid to exitthe cross member via the fluid pressure member.

In one disclosed embodiment, the fluid pressure member comprises apressure relief valve mounted directly to the cross member. The pressurerelief valve is resiliently biased such that lubricating fluid cannotexit the cross member until the predetermined pressure value isachieved. The pressure relief valve is preferably threaded to thecentral body portion and is centrally positioned on an end face of thecentral body portion or on an edge between adjacent trunnions.

Thus, the subject invention provides a method and apparatus for easilydetecting worn components in a universal joint assembly withoutrequiring the universal joint assembly to be disassembled. These andother features of the present invention can be best understood from thefollowing specifications and drawings, the following of which is a briefdescription.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an overhead schematic view of driveline for a heavy-dutyvehicle.

FIG. 2 is a magnified exploded view of a portion of the driveline fromFIG. 1.

FIG. 3 is a perspective view of a universal joint cross memberincorporating the subject invention.

FIG. 4 is a perspective internal view of one of the needle cups of FIG.3.

FIG. 5 is top cross-sectional view of the cross member of FIG. 3.

FIG. 6 is a side cross-sectional view of another embodiment of a crossmember incorporating the subject invention.

FIG. 7 is side view shown in partial cross-section of a fluid pressuremember in a first position.

FIG. 8 is side view shown in partial cross-section of a fluid pressuremember in a second position.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

A heavy-duty vehicle 10 includes a powertrain assembly, shown generallyat 12, that transfers driving power from an engine 14 to a plurality ofwheels 16. The engine 14 is operably coupled to a transmission 18 as isknown in the art. A driveline assembly 20, including at least onedriveshaft 22, is used to transfer driving power from the transmission18 to a drive axle assembly 24 that supports the wheels 16. The driveaxle assembly 24 can be a single drive axle (not shown) or can be atandem drive axle as shown in FIG. 1. The tandem drive axle includes aforward-rear axle 24 a and a rear-rear axle 24 b that are interconnectedto each other.

Preferably, due to the long wheelbase required for heavy-duty vehicles10 and/or due to the use of a tandem drive axle, a plurality ofdriveshafts 22 are used to connect the transmission 18 to the drive axleassembly 24. It should be understood however, that while multipledriveshafts 22 are preferred, a single driveshaft 22 could be used toconnect the transmission 18 to a single drive axle for lighter dutyapplications.

FIG. 2 shows a typical driveshaft arrangement that includes a firstdriveshaft 22 a connected to the transmission 18 at one end andconnected to a second driveshaft 22 b at an opposite end. The seconddriveshaft 22 b is connected to the drive axle assembly 24 at an endopposite from connection to the first driveshaft 22 a. A thirddriveshaft 22 c is used to interconnect the forward-rear axle 24 a tothe rear-rear axle 24 b. A yoke member 26 is supported on each end ofthe driveshafts 22 a, 22 b, 22 c. A cross member 28 is used tointerconnect adjoining yoke members 26. One cross member 28, coupled totwo (2) yoke members 26, defines a universal joint assembly (U-joint)30.

U-joints allow two adjoining driveline components to be positioned atdifferent angles relative to each other to accommodate relative movementand angular misalignment. Misalignment and relative movement can becaused by adjoining driveline components not being mounted within acommon plane, or can be caused by a driveline component, such as a driveaxle assembly 24, moving relative to adjoining driveline component, suchas a driveshaft 22, in response to interaction with a vehiclesuspension.

The cross member 28 is shown in greater detail in FIG. 3. The crossmember 28 includes a central body portion 32 with a plurality oftrunnions 34 extending out radially from the central body portion 32.Each yoke member 26 is attached to a pair of trunnions 34, as is knownin the art.

Bearing packs or needle cups 36 are installed over each trunnion 34. Theneedle cups 36 include a mounting interface 38 that attaches to the yokemember 26. The cross member 28 shown in FIG. 3 has one exposed trunnion34 and three trunnions with installed needle cups 36. The central bodyportion 32 also includes at least one external lubrication fitting 40through which a lubricating fluid, such as grease, is injected into thecross member 28 to provide lubrication so that the U-joint 30 canoperate properly.

Each needle cup 36 includes an internal cavity 42 that is slidablyreceived over one trunnion 34. A plurality of needle bearings 44 ismounted within the cavity 42. A thrust washer 46 is preferably mountedwithin the bottom of the cavity 42 and a seal assembly 48 surrounds alip of the cavity 42 to seal the lubricating fluid within the crossmember 28.

The cross member 28 includes an internal lubrication channel 50, shownin FIG. 5, which is in fluid communication with the external lubricationfitting 40. The internal lubrication channel 50 includes a centralportion 50 a, trunnion portions 50 b that extend into each trunnion 34,and a fitting portion 50 c that communicates with the lubricationfitting 40. This allows lubricating fluid, which is injected through thelubrication fitting 40, to be communicated through internal lubricationchannel 50 to each trunnion 34, so that the needle bearings 44 can besufficiently lubricated.

A fluid pressure member 52 is supported by the central body portion 32and is positioned to be in fluid communication with the internallubrication channel 50. The fluid pressure member 52 is utilized duringservice operations to detect U-joints 30 that have worn internalcomponents, such as bearings 44 and seal assemblies 48, without havingto disassemble the U-joint 30.

Each of the seal assemblies 48 has a predetermined initial sealing forcewhen the U-joint 30 is first assembled. Over time, as components wearand as the vehicle 10 experiences heavy operating loads and adverse roadconditions, the initial sealing force is reduced. During service,lubricating fluid is injected with a grease gun or other similarmechanism, into the cross member 28 via the lubrication fitting 40. Thisgenerates an internal fluid pressure within the cross member 28. If theseal assemblies are still in good working condition, the internallubrication channel 50 will fill with fluid until fluid is forced toexit via the fluid pressure member 52. Thus, the fluid pressure member52 is responsive to or activated when a predetermined pressure value isachieved within the cross member 28. This predetermined pressure valueis less than the initial sealing force for the seal assemblies 48.

If the seal assemblies 48 are worn and need to be replaced, as theinternal fluid pressure increases, fluid will exit the cross member 28via the defective seal assembly 48, instead of through the fluidpressure member 52. In other words, fluid will exit the cross member 28from a defective seal assembly 48 because the worn seal has a reducedsealing force is less than the predetermined pressure value thatactivates the fluid pressure member 52. Thus, when fluid exits the crossmember from the fluid pressure member 52, the U-joint 30 internalcomponents are still in good operating condition, and when the fluidexits from at least one of the seal assemblies 48, a worn internalcomponent is detected. Thus, a simple external visual inspection can beused to detect internal worn components.

In one embodiment, the fluid pressure member 52 is located at an edge 54of the central body portion 32 of the cross member 28, as shown in FIG.5. The fluid pressure member 52 in this embodiment, is positionedbetween adjacent trunnions 34 and extends out radially from the centralbody portion 32. The internal lubrication channel 50 is formed with achannel portion 50 d that extends to the fluid pressure member 52.

In another embodiment, the fluid pressure member 52 is located centrallyon the central body portion 32, as shown in FIGS. 3 and 6. The internallubrication channel 50 includes a similar channel portion 50 d thatcommunicates with the fluid pressure member. It should be understoodthat the fluid pressure member 52 could be mounted in other positions orlocations on the central body portion 32. Similarly, the externallubrication fitting 40 could also be mounted at other locations on thecentral body portion.

Preferably, the fluid pressure member 52 is a pressure relief 60 valvethat is movable between a sealed or closed position, shown in FIG. 7,and an unsealed or open position, shown in FIG. 8. The pressure reliefvalve 60 includes a longitudinal valve body 62 mounted within a bore 80that extends from an internal end 64 to an external end 66. The internalend 64 of the bore 80 is in fluid communication with the internallubrication channel 50 and the external end of the bore 80 isselectively opened to the external atmosphere when the predeterminedpressure value is achieved within the cross member 28.

The pressure relief valve 60 preferably includes a threaded externalsurface 68 that is threaded into a threaded bore 70 formed within thecross member 28. A resilient member 72, such as a coil spring or othersimilar mechanism, cooperates with a movable cap 74 formed on the valvebody 62. The movable cap 74 is resiliently biased to seal the externalend 66 of the bore 80 under normal operating conditions. During aservice operation, when lubricating fluid is injected into the crossmember 28 and the internal fluid pressure is greater than thepredetermined pressure value, the resilient bias force is overcome andthe movable cap 74 opens. This allows fluid communication to theexternal surface of the cross member 28 via the external end 66 of thebore 80. Once the internal pressure is reduced, the resilient member 72returns the movable cap to the initial position.

The subject invention provides a method and apparatus for easilydetecting worn components in a universal joint assembly that does notrequire disassembly. An additional benefit is that a simple externalvisual inspection can be used to detect internal worn components in theU-joint. Although a preferred embodiment of this invention has beendisclosed, a worker of ordinary skill in this art would recognize thatcertain modifications would come within the scope of this invention. Forthat reason, the following claims should be studied to determine thetrue scope and content of this invention.

1-16. (canceled)
 17. A method for detecting an operating condition of auniversal joint assembly comprising the steps of: (a) injectinglubricating fluid into a cross member having a plurality of trunnionswith seal assemblies coupled to first and second yoke members; (b)detecting a properly operating universal joint when lubricating fluidexits a pressure relief member subsequent to step (a); and (c) detectingan improperly operating universal joint when the lubricating fluid exitsat least one of the seal assemblies subsequent to step (a).
 18. Themethod as set forth in claim 17 wherein step (a) further includesgenerating an internal lubrication pressure in response to injectinglubricating fluid into the cross member via an external lubricationfitting; step (b) further includes activating the pressure relief memberwhen the internal lubrication pressure exceeds a predetermined pressurevalue; and step (c) further includes having a predetermined initialsealing force for each seal assembly that is greater than thepredetermined pressure value and detecting a worn universal jointcomponent when the internal lubrication pressure is less than thepredetermined pressure value and when the lubricating fluid exits atleast one of the seal assemblies.
 19. The method as set forth in claim17 wherein step (a) further includes injecting the lubricating fluidinto the cross member via an external lubrication fitting that isseparate from the pressure relief member.
 20. The method as set forth inclaim 17 including providing the pressure relief member with a componentthat is movable relative to an external surface of the cross member; andwherein step (b) includes detecting the properly operating universaljoint when the component moves from a first position where the componentengages the external surface of the cross member to a second positionwhere at least a portion of the component is moved out of engagementwith the external surface.
 21. The method as set forth in claim 20wherein step (c) includes detecting the improperly operating universaljoint when the component remains in the first position and thelubricating fluid exits at least one of the seal assemblies subsequentto step (a).
 22. The method as set forth in claim 21 includingresiliently biasing the component to remain in the first position byapplying a predetermined force and detecting the properly operatinguniversal joint during step (b) when the predetermined force is overcomeas a result of performance of step (a).
 23. The method as set forth inclaim 17 including forming an internal lubrication channel within thecross member, fluidly connecting the internal lubrication channel toeach trunnion of the plurality of trunnions via trunnion channelportions, mounting an external lubrication fitting to the cross member,fluidly connecting the external lubrication fitting to the internallubrication channel via a first channel portion, and fluidly connectingthe pressure relief member to the internal lubrication channel via asecond channel portion.
 24. The method as set forth in claim 23 whereinstep (a) includes injecting the lubricating fluid into the first channelportion; step (b) includes detecting a properly operating universaljoint when lubricating fluid exits the pressure relief member via thesecond channel portion; and step (c) includes detecting an improperlyoperating universal joint when lubricating fluid exits one of the sealassemblies via a respective trunnion channel portion.
 25. A method fordetecting an operating condition of a universal joint assemblycomprising the steps of: (a) visually detecting a properly operatinguniversal joint assembly when lubricating fluid exits a universal jointassembly from a first location; and (b) visually detecting an improperlyoperating universal joint assembly when lubricating fluid exits theuniversal joint assembly from a second location different than the firstlocation.
 26. The method as set forth in claim 25 including defining thefirst location at a pressure relief member interface and defining thesecond location at a trunnion seal interface.
 27. The method as setforth in claim 26 including providing the universal joint assembly witha cross member having a plurality of trunnions and an externallubrication fitting, forming an internal lubrication channel within thecross member, sealing each trunnion with a seal member, fluidlyconnecting the external lubrication fitting to the internal lubricationchannel, and injecting lubricating fluid into the internal lubricationchannel by way of the external lubrication fitting prior to anoccurrence of at least one of step (a) and step (b).
 28. The method asset forth in claim 27 including mounting the pressure relief member tothe cross member, fluidly connecting the pressure relief member to theinternal lubrication channel, and wherein step (a) includes visuallydetecting a properly operating universal joint assembly when lubricatingfluid exits the pressure relief member and step (b) includes visuallydetecting an improperly operating universal joint assembly whenlubricating fluid exits the seal member from at least one of theplurality of trunnions.